4 cups of Flour (bleached)
1/2 cup shortening
2 tsp. salt
1 tsp. baking powder
Mix all these ingredients together until the shorting has basically disappeared/ worked into the flour really well.
Next you will add 2 cups of warm water. Now this part is kind of tricky, if the water is too cold your dough will come out kind of hard and not easy to knead but if it is too warm or hot it will become so sticky that you will need to add more flour and then if you add too much flour again your dough will just become kind of hard. So you have to be very careful about getting it just right. Now the other thing is I don't add all 2 full cups of water, I start off by adding between 1 to 1 1/2 cups first and need that in and slowly add in more little by little. Then after it is kneaded and well mixed I cover with some plastic wrap and let it '"rest" for about 15 min. (gives me a chance to put everything away, and get things ready). Then you roll the dough out into little balls and then once all the dough is rolled into little balls you can start rolling out your tortillas.
As for making them round, it just takes practice I do keep flipping the dough over and over as when I'm rolling it out and then kind of stretch it out in my hands like the do with pizza crusts (with out the throwing in the air, I think I'd end up wearing the dough if I ever tried that!).
You definitely want a good solid rolling pin, I dislike the ones with handles, I feel that I can't apply even pressure towards the middle. Just a solid piece of wood.
Anyway, I don't know if any of this will make sense. It all looks/reads complicated but it really isn't. If you have any questions feel free to ask. They definitely are something you need to make over and over to get really good at.